Telecommunication service providers are currently migrating circuit-switched voice services to packet networks, which use Voice over Internet Protocol (VoIP) to support services. In light of the multimedia capabilities afforded packet communications and in an effort to generate revenue, the service providers are offering a litany of communication related services along with the voice services. To control and track these services, the service providers are employing a service delivery platform referred to as the IP Multimedia Subsystem (IMS) and defined by the Third Generation Partnership Project (3GPP). Using the Session Initiation Protocol (SIP), the service providers are able to converge wireline and wireless services as well as support the legacy time division multiplexed (TDM) networks of the Public Switched Telephone Network (PSTN). The service providers are employing IMS as an integral part of their respective carrier networks. As such, IMS is hosted in the carrier network.
Traditionally, a significant source of revenue for service providers is derived from businesses, which generally have their own private networks. These private networks are generally referred to as enterprise networks and use their own addressing or numbering plan. Although enterprise networks are connected to the carrier networks of the PSTN, the interplay between the enterprise networks and the carrier networks has traditionally been limited. As IMS is being deployed, the interplay between the enterprise networks and the carrier networks remains limited because of addressing and security issues associated with the enterprise network.
In many instances, the enterprise network is capable of providing various services to authorized users that are not made available by the carrier network, and vice versa. Authorized users who have roamed outside of the enterprise network and are currently supported by the carrier network no longer have access to the enterprise services that are available to those within the enterprise network. Those users that are served by the enterprise network cannot take advantage of the services provided by the carrier network. As such, there is a need for a way to allow authorized users to gain access to enterprise and carrier services regardless of their location. There is a further need for a way to facilitate greater interaction between enterprise and carrier networks and resolve the addressing issues caused by the different and often incompatible addressing schemes of the respective networks.